ORIGIN: Metal Creation and Evolution from the Cosmic Dawn

ORIGIN is a proposal for the M3 mission call of ESA aimed at the study of metal creation from the epoch of cosmic dawn. Using high-spectral resolution in the soft X-ray band, ORIGIN will be able to identify the physical conditions of all abundant elements between C and Ni to red-shifts of z=10, and beyond. The mission will answer questions such as: When were the first metals created? How does the cosmic metal content evolve? Where do most of the metals reside in the Universe? What is the role of metals in structure formation and evolution? To reach out to the early Universe ORIGIN will use Gamma-Ray Bursts (GRBs) to study their local environments in their host galaxies. This requires the capability to slew the satellite in less than a minute to the GRB location. By studying the chemical composition and properties of clusters of galaxies we can extend the range of exploration to lower redshifts (z ~ 0.2). For this task we need a high-resolution spectral imaging instrument with a large field of view. Using the same instrument, we can also study the so far only partially detected baryons in the Warm-Hot Intergalactic Medium (WHIM). The less dense part of the WHIM will be studied using absorption lines at low redshift in the spectra for GRBs.

💡 Research Summary

ORIGIN (Origin: Metal Creation and Evolution from the Cosmic Dawn) is a proposal submitted to ESA’s M3 mission call, aiming to map the full life cycle of metals—from their first synthesis in the earliest stars to their present distribution in galaxies, clusters, and the intergalactic medium. The mission’s scientific thrust is built around four inter‑related questions: (1) When and where were the first metals produced? (2) How does the cosmic metal budget evolve with time? (3) In which cosmic reservoirs (galaxies, clusters, WHIM) do the bulk of metals reside? (4) What role do metals play in the formation and feedback processes that shape large‑scale structure?

To answer these, ORIGIN combines three key payload elements: a Transient Event Detector (TED) – a coded‑mask imager covering 5–150 keV with a sensitivity of 0.4 ph cm⁻² s⁻¹ (10 s) that will detect ~2000 GRBs over five years and provide arc‑minute localisations; a Cryogenic Imaging Spectrometer (CRIS) – a soft‑X‑ray (0.2–2 keV) micro‑calorimeter delivering 2.5 eV energy resolution, a 30‑arcmin field of view, and a large effective area below 1 keV; and a Burst InfraRed Telescope (BIRT) – an IR spectrograph (0.8–5 µm) that captures the Lyman‑break and low‑ionisation metal lines, supplying redshifts and complementary abundance diagnostics.

The operational concept is two‑fold. First, the “rapid‑response mode” triggers on a GRB detection, slews the spacecraft in < 60 s, and points CRIS and BIRT at the afterglow. Simulations show that even a z = 7 burst with an integrated 0.5–10 keV fluence of 4 × 10⁻⁶ erg cm⁻² will display narrow resonant lines of Fe, Si, S, Mg, and other abundant elements, enabling precise abundance ratios and redshift determination. The IR telescope simultaneously records the Lyman‑break, guaranteeing redshift confirmation even for metal‑poor environments. Second, the “wide‑field survey mode” exploits the large grasp (area × field) of CRIS to map the hot intracluster medium (ICM) out to the virial radius and to search for WHIM emission over a wide sky area. By combining emission‑line maps with absorption‑line studies along GRB sightlines, ORIGIN will quantify the metal content of the diffuse intergalactic filaments.

Scientific returns are manifold. The GRB afterglow spectra will provide the first direct “fingerprints” of Population III nucleosynthesis, constraining the initial mass function of the first stars. By assembling a statistical sample of ~400 GRBs per year across the full redshift distribution, the mission will chart the rise of star formation and metal enrichment during the epoch of re‑ionisation (z > 6). Cluster observations will trace the evolution of elemental ratios (e.g., Fe/Si, O/Fe) from the present back to z ≈ 0.2, revealing how supernovae and AGN feedback have redistributed metals over gigayear timescales. WHIM measurements will address the long‑standing “missing baryon” problem by determining what fraction of the cosmic baryon budget resides in warm‑hot filaments and how enriched those structures are.

Technically, ORIGIN faces challenges in achieving sub‑minute repointing, maintaining the ultra‑low temperature required for the micro‑calorimeter, and securing sufficient signal‑to‑noise in the brief afterglow phase. The proposal mitigates these risks with redundant attitude‑control loops, a backup cryocooler system, and observation strategies derived from extensive end‑to‑end simulations.

Compared with existing or planned missions, ORIGIN occupies a unique niche. Swift offers rapid GRB localisation but lacks high‑resolution spectroscopy; Astro‑H (Hitomi) provides excellent spectral resolution but a small field of view and slower response; the International X‑ray Observatory (IXO) would deliver large effective area and angular resolution but not the fast slewing required for transient science. ORIGIN’s combination of (i) ultra‑fast repointing, (ii) a wide 30‑arcmin field, and (iii) cryogenic spectroscopy with 2.5 eV resolution gives it unprecedented capability to conduct both transient and survey science in the soft X‑ray band.

In summary, ORION (sic—ORIGIN) promises to open a new window on cosmic chemical evolution, delivering the first comprehensive, high‑resolution, multi‑wavelength inventory of metals from the cosmic dawn to the present, and thereby addressing fundamental questions about the birth of the first stars, the growth of galaxies and clusters, and the whereabouts of the Universe’s missing baryons.